- Researchers sought to determine whether MRI images could be used instead of CT images to calculate the skull corrections needed during focused ultrasound brain treatments.
- The collaborative team compared the imaging results using two types of calculations and six measurement tools.
- The group determined that MRI could effectively be used to create MR-simulated CT images.
- Making the change could ultimately help eliminate the cost and radiation exposure associated with CT scans.
A collaborative group of researchers from Stanford University, the University of Virginia, and the Focused Ultrasound Foundation sought to determine whether MRI images could be used instead of CT images to calculate the phase corrections that are needed when skull bone diverts focused ultrasound waves during brain treatments.
First, the team used two methods to compute phase correction data: a hydrophone (the gold standard) and ray tracing from a CT (the current standard of care). They then used two different MR image techniques to determine an alternative phase correction. Hydrophone measurements were then used to evaluate all four phase correction methods.
After analyzing the data, the researchers determined that MRI could effectively be used to create MR-simulated CT images to correct phase aberrations when using focused ultrasound for brain ablative or blood-brain barrier opening treatments. The use of the MR-simulated CT images also reduced the possibility of creating errors when co-registering CT and MR images.
Because CT exposes patients to ionizing radiation and can create co-registration errors with MRI, the group concluded that MR-simulated CT images would be a preferred method.
“The ability to acquire MR images at the time of treatment for both targeting and skull correction is an important improvement in patient care, said John Snell, PhD, one of the contributing authors and the Foundation’s former Brain Program Technical Director. “Focused ultrasound brain treatments can be made less invasive (eliminate ionizing radiation from CT), with improved efficiency, accuracy, and safety.”
“It would make overall patient treatment times shorter if the medical team did not need to acquire a CT beforehand,” added David Moore, the Brain Technical Program’s senior project engineer. “Although most patients have a CT from their previous medical treatments, this is not always a guarantee, especially if they are being treated at a new facility.”